Operator #5, ìAmericaís Undercover Ace,î was Jimmy Christopher, a Secret Service agent defending the United States from all manner of threats for nearly six years. The Popular Publicationspulp hero was joined by newswoman Diane Elliot, young assistant Tim Donovan and others to battle an array of invaders, most notably the Purple Emperor, dictator Rudolph I of Balkaria.

With a rapier hidden in his belt and an explosive-packed skull ring, Jimmy Christopher lead the charge as Operator #5 against such foes as ìThe Yellow Scourge,î ìLegions of Starvation,î ìThe Red Invadersî and ìHosts of the Flaming Death.î But it proved to be the Purple Invasion that gave readers what some have described as the War and Peace of the pulp magazines and Operator #5ís zenith.

From August 1936 through March 1938, Christopher, joined by the lovely Diane Elliot, who earned a place as a secret agent in the series, and teen sidekick Tim Donovan, tackled dictator Rudolph I of Balkaria (a thinly disguised Germany), who was known as the Purple Emperor, and his varied minions.

In addition to Elliot and Donovan, Christopher sometimes was assisted by:

John Christopher, his father, who was a retired intelligence agent once known as Operator Q-6, despite a bullet lodged dangerously close to his heart.

Nan Christopher, Jimmyís twin sister.

Z-7, the chief of U.S. intelligence, who eventually is replaced by Jimmy Christopher.

Crowe, a man-servant under the employ of Carleton Victor, a world-famous photographer (who actually is a guise for Jimmy Christopher).

Davis wrote the initial 20 adventures, with Tepperman picking up the reigns with the December 1935 number, ìRaiders of the Red Death.î Five issues and six months later, Teppermanís Purple Invasion cycle began with ìDeathís Ragged Army.î It ended after 13 novels with the emperorís defeat in ìThe Siege that Brought the Black Death,î in March 1938.

Tepperman got in one more story before Rogers took over as author of the final nine published novels.